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The facility’s roof consists of 3,000 tons of structural steel that support a PTFE membrane. The PTFE fabric is suspended from 430-foot-long structural steel trusses that support an array of structural steel v-columns. Design architect Populous designed the roof form and then worked in tandem with Walter P Moore to create the roof’s structure and subdivide it into trusses. All images and renderings courtesy Populous

Net-zero energy pioneers on the el-hi frontier

Getting to net-zero is not easy, but the promise of eliminating energy bills and using state-of-the-art technology as a learning lab can make a compelling case to reach for net-zero.

September 07, 2012 |

By Peter Fabris, Contributing Editor

Net-zero may seem beyond the budgets of most K-12 school districts, but a couple of trailblazers have found the means to construct schools designed to produce as much power as they use.

The new $20 million, 88,693-sf Colonel Smith Middle School in Ft. Huachuca, Ariz., takes daylighting to the highest level. Every regularly occupied space has a window, skylight, or clerestory glazing for layered daylighting. To hold down the cooling load, the building obtains most of its sunlight from the north sky through clerestory windows. On the south exterior wall, exterior overhangs prevent direct solar exposure in the summer, while allowing passive solar heating in winter. Locker rooms and other support spaces have shaded high-wall translucent fiberglass panels to provide privacy. Lighting energy use is expected to be 80% less than that of a standard school building.

Energy is recovered from locker room exhaust to pre-heat or pre-cool supply air delivered to locker rooms. Solar panels heat domestic water for locker rooms and the kitchen. PVs were obtained through a power purchase agreement. “We didn’t have net-zero in mind when we were starting out,” notes Dr. Ronda Frueauff, Superintendent of the Ft. Huachuca Accommodation School District. That changed as the design committee evaluated the affordability of each green element. Only geothermal was ruled out as cost-prohibitive.

Geothermal is, however, a key component of the Lady Bird Johnson Middle School in Irving, Texas, with 530 geothermal wells and 105 water-source heat pumps. The school is powered by 2,988 rooftop solar panels and 12 wind turbines. Opened in August 2011, the $29 million, 152,000-sf school cost about 12% more to build than one of traditional construction. School officials expect to recoup their investment in 10-12 years.

“We didn’t have net-zero in mind when we were starting out.”

Both schools incorporate green features into lesson plans. The Texas school features museum-type displays along the main hallway highlighting geothermal, solar, and wind technology, along with water efficiency. Students can get a close-up view of the PVs from a roof observation deck.

Getting to net-zero is not easy, but the promise of eliminating energy bills and using state-of-the-art technology as a learning lab can make a compelling case to reach for net-zero. +

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